add standard repository field format in yotta init, upgrade single-string style fields
add standard repository field format in yotta init, upgrade single-string style fields

ARMmbed/yotta,bridadan/yotta,BlackstoneEngineering/yotta,ntoll/yotta,autopulated/yotta,iriark01/yotta,stevenewey/yotta,theotherjimmy/yotta,ntoll/yotta,bridadan/yotta,theotherjimmy/yotta,autopulated/yotta,eyeye/yotta,eyeye/yotta,iriark01/yotta,BlackstoneEngineering/yotta,ARMmbed/yotta,stevenewey/yotta